Résumé:
The present study aimed to extract polyphenols from pomegranate (Punica granatum L.) peel extract (PPE) by maceration
using three different solvants: acetone 70%, ethanol 70% and methanol 70% (v/v). The antioxidant capacity potential was
determined by scavenging activity of free radicals (DPPH) and ferric reducing power (FRAP) assays. The antimicrobial
activity of PPE was evaluated against six oral pathogens isolated from dental caries and supragingival plaque (Streptococcus
mutans, Enterococcus faecalis, Gemella morbillorum, Staphylococcus epidermis, Enterococcus bugandensis and Klebsiella
oxytoca). The highest total phenolic and flavonoid contents were obtained with ethanolic PPE (204.67 ± 15.26 26 mg gallic
acid equivalents (GAE)/g dry weight (DW), 67.67 ± 1.53 mg quercetin equivalent (QE)/g DW respectively). The highest
proanthocyanidin content was observed with acetonic extract (220 ± 17.32 mg catechin equivalent (CE)/g DW). The
phenolic profile of ethanolic PPE was determined by HPLC analysis; peduncalagin, punigluconin and punicalagin as a
predominant ellagitannin have been identified. The highest scavenging activity (87.37 ± 1.36%) was exhibited by ethanolic
PPE with the lowest IC50 value (220 ± 14µg/ml) for DPPH, whereas the highest reducing power assay was observed with
acetonic PPE with a value of 1.48 at 700 nm. The antibacterial activity was investigated by microdilution method, all
bacteria were sensitive to the extract with MIC (minimum inhibitory concentration) ranging from 0.0125 to 100 mg/ml, the
Gram-positive bacteria are the most sensitive. Antibiofilm activity of ethanolic PPE was tested by crystal violet. The
maximum biofilm inhibition was observed at the highest concentration of the extract (MIC) with E. faecalis (91.95%) and S.
epidermis (90.7%). Results indicate the potential application of PPE as antioxidant and antibacterial agent against oral
pathogens and that it has great potential for prevention and treatment of dental caries.
